An improved MCSCF method

Roothaan, C. C. J.; Detrich, John; Hopper, Darrel G.

doi:10.1002/qua.560160811

Cited by 11 publications

(9 citation statements)

References 22 publications

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“…Alternative optimization schemes have recently been proposed by Dalgaard and Jorgensen (1978), Yeager and Jorgensen (1979), and Roothaan et al (1979). Unitary transformations of the molecular orbitals and the CI coefficients are generated by the use of exponential operators.…”

Section: The Multiconfiguration Scf Methods (Mcscf)mentioning

confidence: 99%

The Calculation of Potential Energy Surfaces for Excited States

Hirst¹

1982

Advances in Chemical Physics

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Section: The Multiconfiguration Scf Methods (Mcscf)mentioning

confidence: 99%

The Calculation of Potential Energy Surfaces for Excited States

Hirst¹

1982

Advances in Chemical Physics

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“…These computations have been carried out using a multi-configurational self consistent field (MCSCF) method. [18][19][20] To achieve better accuracy for the PECs of states with outer valence holes, in addition to MCSCF, some theoretical studies employ the multi-reference configuration interaction (MRCI) method. [21][22][23] In this work, for completeness, we also compute the PECs of N 2 states with one or two outer valence electrons missing.…”

Section: Introductionmentioning

confidence: 99%

Potential Energy Curves of Molecular Nitrogen for Singly and Doubly Ionized States with Core and Valence Holes

Bhattacharya

Shamasundar

Emmanouilidou

2021

Preprint

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Our manuscript, presents the computation of potential energy curves of all possible singly and doubly ionized states of molecular nitrogen. Accurate representation of the potential energy curves of ionized states of N2 is essential to explicitly treat coupled electron-nuclear dynamics. In this work, we compute the potential energy curves of the valence as well as the core and inner valence singly and doubly ionized states of N2. These curves pave way to study the interplay between photoionization and Auger spectra when molecular nitrogen interacts with free electron lasers.Computation of inner valence or core ionized potential energy curve is not trivial due to the well-known problem of variational collapse of the wavefunction to the lowest energy state. We circumvent this problem by implementing a two-step optimization scheme within the multi-configurational self-consistent field approach. Such a two-step optimization scheme has been previously implemented to compute potential energy curves of core ionized states of di-atomic molecules with one hole. Herein, we show the general applicability of this two-step optimization method by computing potential energy curves of both singly and doubly ionized states of N2 with valence and core holes. Calculation of potential energy curves for core ionized polyatomic systems are scarce. Moreover, our approach is system independent and can be easily extended to calculate multiple-core ionized states. To the best of our knowledge, this is the first calculation of potential energy curves for doubly ionized states of a diatomic molecule with two core (or inner valence) holes.

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“…With this additional restriction, the APIG wavefunction is a seniority-zero wavefunction, and can be viewed as a mean-field parameterization of the doubly-occupied configuration interaction (DOCI) wavefunction. [53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] In DOCI, every wavefunction is written as a linear combination of Slater determinants in which every orbital is either doubly-occupied or empty.…”

Section: Introductionmentioning

confidence: 99%

Strategies for extending geminal-based wavefunctions: Open shells and beyond

Johnson

Limacher

Kim

et al. 2017

Computational and Theoretical Chemistry

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We discuss some strategies for extending recent geminal-based methods to open-shells by replacing the geminal-creation operators with more general composite boson creation operators, and even creation operators that mix fermionic and bosonic components. We also discuss the utility of symmetry-breaking and restoration, but using a projective (not a variational) approach. Both strategies-either together or separately-give a pathway for extending geminals-based methods to open shells, while retaining the computational efficiency and conceptual simplicity of existing geminal product wavefunctions.

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An improved MCSCF method

Cited by 11 publications

References 22 publications

The Calculation of Potential Energy Surfaces for Excited States

The Calculation of Potential Energy Surfaces for Excited States

Potential Energy Curves of Molecular Nitrogen for Singly and Doubly Ionized States with Core and Valence Holes

Strategies for extending geminal-based wavefunctions: Open shells and beyond

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